Bulky dyed yarns



United States Patent O 3,495,392 BULKY DYED YARNS Raymond J. Elia, Geneva, Switzerland, and George D. Null, Landenburg, Pa., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Continuation-impart of application Ser. No. 671,602, Sept. 29, 1967. This application June 26, 1968, Ser. No. 740,037

Int. Cl. D02g 3/02; D021 1/22; C08g 19/00 U.S. Cl. 57-140 4 "Claims ABSTRACT OF THE DISCLOSURE Dyed synthetic polycarbonamide yarns are prepared that are suitable for the production of woven fabrics having the visual and tactile aesthetics of silk yarn-dyed fabrics.

BACKGROUND OF THE INVENTION This application is a continuation-in-part of application Ser. No. 671,602, filed Sept. 29, 1967.

Yarn-dyed natural silk fabrics are stiff and not excessively supple. Because of this relatively stiff nature, these fabrics are ideally suited for fabrication into womens gowns and dresses of outstanding quality. However, garments made of natural silk, although having outstanding appeal, lack the durability characteristics of garments made from synthetic filaments.

Numerous attempts have been made to prepare silklike fabrics from synthetic polyamide yarns. Recently yarn has been developed which comprises a plurality of oriented synthetic continuous polyamide filaments at least some of which differ in shrinkability from other of said filaments. A particularly preferred yarn is the mixed filament yarn wherein both constituent types are polyamides derived from the PACM diamine family. Suitable PACM diamines include bis(4 aminocyclohexy1)methane and his 4 amino(cyclohexyl)ethane. In yarn dyeing operations, mixed filament yarns from PACM polyamides tend to generate less shrinkage tension than other mixed continuous filament yarns. Consequently, the new PACM yarn as produced for use in piece-dyed fabrics are not entirely satisfactory for yarn dyeing on the commonlyused collapsible bobbins available in the textile trade. Dyed yarns prepared from mixed PACM yarns of this type when dyed on bobbins have very poor uniformity in bulk and dye-ability from the inside of the package to the outside. On the other hand, such yarns would be expected to be very useful if properly handled because of the development of differential shrinkage during the yarn dyeing operation.

SUMMARY OF THE INVENTION In accordance with the present invention a yarn is pro: vided comprising a plurality of drawn, oriented synthetic polymer filaments, one group of which filaments differs in shirinkability from another group of said filaments, and all of which filaments consist of at least 50% by weight of polymer units of the formula wherein X is 1 or 2, Y is an integer in the range of 7-14 inclusive, R is the same or different and of the class of hydrogen and methyl, at least 40% by weight of the diamino polymer constituentbeing of a trans-trans stereoisome ric configuration. The yarn subjected to the process 'ice of the invention should exhibit a differential shrinkage between said groups of filaments of at least 1.5% when placed under a 4 milligram per denier load in boiling water for about 30 minutes, and said shrinkage differential should increase on heat setting at higher temperatures under the same load. The load is removed before making the -DFL measurement as described below. The bulked yarn of the invention has a twist multiplier between 0.27 and 1.50, a liveliness multiplier less than 0.4, and has 3 to 10% differential filament length.

The yarn of the invention is prepared by twisting the specified mixed filament PACM polyamide yarn on conventionl equipment to obtain a twist multiplier of about 0.27 to 1.5. The twist is then set by heating the yarn at constant length at a temperature of at least 70 C. but less than 105 C. to reduce the liveliness multiplier to below 0.4. Finally, the twist-set yarn is bulked by treating under shrinkage conditions at temperatures higher than in the twist-setting operation, thereby promoting the development of 3 to 10% differential filament length between the two filament species in the mixed filament yarn. Typical polymers for use in the yarn of the invention are the polyamides prepared from bis(4 aminocyclohexyl) methane and sebacic, azelaic, or dodecanedioic acid.

The proportion of high to low shrinkage filament required to obtain the desired results will vary depending on the difference in shrinkage potentials and on other factors such as filament denier, etc. In general, at least 25% by Weight of the higher shrinkage filaments should be present and similarly at least 25 of the low shrinkage filaments should be present.

DETAILS OF THE INVENTION The different groups of filaments in the yarn which provide the prescribed differential shrinkage and resulting differential filament length in the yarn after shrinking, are provided by combining a first group of filaments consisting essentially of a polyamide having repeating units of Formula I and a second group of filaments consisting of a polyamide containing from 50 to mol percent of the repeating units of Formula I and 5 to 50 mol percent of units of another polyamide prepared from a member of a class consisting of (1) the same diamine of Formula I with a different dicarboxylic acid and (2) the same dicarboxylic acid of Formula I with a different diamine. Physical differences between the two groups of filaments may also be used to promote differences in filament length.

The preparation of PACM polyamides is described in Gadecki and Speck US. Patent 3,249,591, Bolton & Kirk US. 2,512,606, and in British Patent No. 1,091,007. The mixed yarns preferably are spun by extruding the two polymer species from adjacent holes in the same spinneret. The mixed yarns are drawn and oriented by conventional methods.

In the process of the present invention the mixed filament PACM yarn is twisted on a conventional downtwister or uptwister to a twist multiplier level between about 0.27 and 1.50 allowing for shrinkage in the relaxed heat treatment later on. The twisted yarn is heat-treated (twist-set) on a bobbin or other rigid core at constant length to stabilize the yarn, i.e., to reduce liveliness in subsequent steps. Twist setting can also be done in a continuous process by running the yarn through a heated zone. The twist-setting may be done by exposure to wet or dry air at 70 to C., but preferably by exposure to moist air. The temperature, moisture content, and time exposure are regulated to produce a yarn with a liveliness multiplier, as hereinafter defined, of less than 0.40, preferably less than 0.16.

In the next step the twist set yarns are treated at still higher temperature under very low tension to promote development of differential filament length and increased bulk. Preferably the twist-set yarns are shrunk by heating under low tension with steam under superatmospheric pressure at a temperature of from about 120 to 140 C. The temperature should be sufficiently high to preclude any Significant additional shrinkage during dyeing. Low tension may be assured by winding the twist set yarn in a uniform manner on a collapsible coreand shrinking the yarn in package form in an autoclave.

The pre-shrunk yarn may then be dyed in a conventional manner. Preferably, it is package-dyed in an autoclave under superatmospheric pressure in the presence of a dye carrier for the filaments. Uniform dyeing is obtained by reversibly forcing the dye bath liquor through the package under pressure in a conventional manner. Through conventional techniques the twisted, dyed, bulked yarn may then be made into a fabric which requires no further stabilizing treatments such as heat-setting.

The woven fabrics of this invention upon removal from the loom are comprised of dyed yarns of filaments having a differential length of from about 3 to Yarns removed from the fabric have a substantially lower tendency to retain weave crimp, than do yarns removed from a piece-dyed fabric of similar construction. The fabrics of this invention have the stiffness and body of yarn-d-yed fabrics prepared from natural silk combined with the performance and durability of synthetic polycarbonamide filaments. If desired, the fabrics may be softened by heatsetting at off-loom width at 170 to 190 C.

Yarn twist has a 2-fold role in this invention (1) to give the desired fabric aesthetics (e.g., higher twist-harder fabric, lower twist-softer fabric), and (2) to give good operability in packaging and weaving. For example, at least aobut 10 turns per inch (3.9 per cm.) are required in 60 denier warp yarns (twist multiplier 1.05) to get acceptable weaving, with at least about 2.5 turns per inch (0.99 per cm.) for 60 denier yarns in the fill twist multiplier .27).

The yarns must not be so highly twisted that the twist restraining forces are so high as to prevent the desired differential filament shrinkage to occur. For this reason, a twist multiplier of 0.27 to 1.50 is normally preferred in the filling. Twist multiplier (T .M.) is defined as Twist per inch yarn denier At twist setting temperatures or conditions other than those specified, yarn liveliness presents problems in han= dling, making uniform control difficult and creating undesirable non-uniforrnities in the resulting yarn and fabric. Higher twisting setting temperatures than those specified are detrimental to proper development of bulk and differential filament length dun'ng shrinking. Careful control of shrinking conditions is important. Sufficiently high temperatures must be employed to obtain the desired shrinkage differential between the filaments but conditions must not be so severe that undue degradation, discoloration, and loss of filament tensile properties results.

In a preferred embodiment of the process of this invention the treating steps are performed on the yarn package for convenience. The yarns are twisted and packaged and then subjected to the twist-setting operation in a conventional manner, for example in a heat-setting oven. The twist-setting facilitates yarn handling in package formation for the subsequent shrinkage treatment. The yarn must be shrunk under low tension for the proper amount of shrinkage to occur. Excessive variations in tension cause shrinkage variations and therefore variations in the differential filament length. In order to obtain sufficiently low shrinkage tension in package form the twist-set yarn may be wound on an easily compressible core, for example a collapsible paper core. The amount of shrinkage Which results is dependent on the yarn tension, temperature, pressure and time of exposure under the shrinkage conditions. The shrunk yarn is then substantially dimensionally stable throughout the following dyeing operation. This dimensional stability is necessary to insure uniform dyeing. Until the shrinkage step, the yarn handles like a normal straight, continuous filament yarn. During shrinkage the yarn shrinks and develops differential filament lengths. After shrinking the yarn is wound onto yarn-dye tubes and can be pressure dyed in a conventional manner, preferably with a suitable dye carrier such as butylbenzoate or lauryl alcohol. Dyeing under these conditions does not result in any substantial decrease in the differential filament lengths. The dyed yarns are wound onto cones with application of a lubricating oil to facilitate subsequent textile operations. The weaving or knitting is then performed in a conventional manner.

The packaging and winding operations in preparing these yarns can be done on any suitable winding equipment which gives uniform tension control and permits formation of relatively soft packages. Suitable equipment should give uniform tension control within the range of about :05 grams and permit formation of a package having a hardness in the range of 15-30 units as measured by a Type O-2 Durometer made by the Shore Instrument Company of New York.

To insure acceptable levels in uniformity of shrinkage in package form, packages should have hardness levels in the 15-20 range for 30 denier counts and 20-30 hardness levels for 60 denier yarn counts when measured in the form of a 0.4 lb. package. Yarn running tensions in the 0.5-1.0 range for the 30 denier counts and 1.5-3.0 grams for the 60 denier count are suitable.

The yarn packages are preferably shrunk by heating in an autoclave with superatmospheric steam at a temperature of to 132 C., for example for 30 minutes. Such conditions sufficiently stabilize the yarn so that little additional shrinkage will occur during dyeing. A typical autoclave shrinkage cycle for 0.4 lb. packages is three minutes under vacuum of 27 inches (75 mm.) of mercury, injection of steam at 127 C. for 30 minutes under a pressure of 26 l bs/in? gauge (2.9 kg./cm. followed by vacuum as above for 8 minutes and release of vacuum over a period of 2 minutes. The resulting yarn packages show uniform shrinkage throughout. The actual shrinkage level obtained will be dependent upon the nature of the filaments in the yarn. Normally total shrinkage levels of 10-12% are suitable resulting in a differential filament length of about 7-8%. At lower levels of total shrinkage, correspondingly lower degrees of differential filament length will result.

The yarns used for this invention contain filaments which differ in length as the result of different shrinkages. The percent difference in filament length (DFL) between the high and low shrinkage filaments is determined by cutting a 40 cm. strand from the yarn package after shrinking, doubling the strand, and tying the free ends together to form a loop about 19 cm. long. The free ends above the knot are taped to a vertical meter rule and the lengths of isolated individual filament loops are measured by hanging a 0.4 milligram per denier weight in a loop. At least 5 low shrinkage and 5 high shrinkage filaments are measured in this manner. Percent DFL is calculated from the following equation:

where L is the average length of the longer filaments and L is the average length of the shorter filaments.

For measurement of DFL on the shrunk twisted yarns a different procedure was used. A 20 inch length of yarn was doubled and the free ends tied and taped to a vertical meter rule. A 0.6 gram paper clip was employed as a weight to straighten the yarn. The yarn length (L was then measured. The yarn was then extended by pulling Percent FDL= on the paper clip until the point where all evidence of loopiness disappeared and the yarn length (L was measured. These values are then inserted into the percent DFL equation.

Twist liveliness of (T.L.) is determined at 21 C. and

show uniform development of DEL throughout the package.

The twist-set shrunk yarns were wound without difficulty into dye packages at 0.5 gm. tension onto perforated stainless steel tubes for pressure dyeing The yarns were 75% relative humidity. Samples are removed tangentialscoured and then pressure dyed in a conventional packly from the package by rolling the package so that no age dyeing manner, dyeing at 240 F. (1'l5.5 C.) for 90 twist is added or removed. A pointed weight of 1 g. is minutes with 5% Resolin Blue FBLD (Color Index fastened to one end of a suspended strand which is of Disperse Blue-71) and 5% (on weight of fiber) Charknown length (about cm.). The yarn is allowed to lab DAG-888, a commercial butyl benzoate dye carrier. untwist as a result of the action of the weight. The num- 10 There is substantially no change in yarn DFL upon dyeber of turns is counted during unwinding to an equilib- No dye non-uniformity (dye junction) is observed rium point. Any rotation past the equilibrium point is m satin fabrics in which outside, middle and inside yarns not counted by taking the net number of turns to equilibfrom the y Package are Woven y' rium. The twist liveliness is finally calculated'by divid- TABLE 1 ing the net turns to equilibrium by the original length A B C D E F of the test sample in cm. before unwinding. The answer is expressed inturns/cm. In 60 denier yarns of the in- 'lwviiltsettemp-1C vention, the twist liveliness is below 0.6 turns/cm. iiiil iijjIIIIIIIIIIIIIIIIIZI 64. 33 g5 S8 512 All yarns of the invention have a liveliness multiplier %Eif% i gj: F gg 5 3 2 2 1 0 below 0.4, preferably below 0.16. The liveliness multi- After preshrinkag e 8.5 6.8 5.2 5.0 4 s 3.6 plier (L.M.) is a factor which relates twist liveliness to 4 9 denier: *Saturated steam.

L M T.L.X\/denier EXAMPLE II 28.8 An S-hardness satin fabric was woven using the dyed Yarns of equal liveliness multiplier have approximately yam Prepared as described In EXamPIe 1B for the filhng' an equal ability to kink during the relaxed heat treatment The yam had been twisted 5 mugs/Inch (1'97 turns/ (e.g., on collapsible bobbin). Liveliness may be also and Set as descnbed at 77 and preshrunk i 126 C. The yarn had a DFL of 6.5%. Two ends of this udgedsub ectively as in Example I. 5 The following examples illustrate the present invenyam were led and twlsted S turns/Inch tion turns/cm.) 1n the ply. The warp yarn was prepared as m Example I, but with 30 denier 18 filament with 15 turns EXAMPLE I Z tw1st per lIlCh (5.9/cm.). The Warp was twist set and a Startlng matellal there P p d y shrunk under the same conditions as the filling. The fabric sRlflnlng {hfollgh Separate 110165 a Fmglfi p f i a was of 3.74 oz./yd. (126.7 gms./meter construction mixed shrlnkage yarn of about denier and containing having 350 ends/inch warp and 98 picks per inch fill (138 36 filaments. Eighteen of the filaments were a polymer of ends per cm. warp and 40 picks per cm. fill). bis (4-aminocyclohexyl)rnethane containing by Fabric properties off the loom, after framing at olfweight of transtrans-lsomer and dodecane dioic acid, 40 loom width at 149 C. for 1 minute, after heat-setting at and the other eighteen filaments were a copolymer of off-loom width at 180 C. for 30 seconds followed by 1 the same diamine with weight percent dodecane dioic minute at 190 C. and after semi-decating 1 minute with acid and 10 weight percent of isophthalic acid. The filasteam-2 minutes vacuum, are shown in Table H.

TABLE I1 Semi-decated Fabric property Ofi m Framed Heat-set after heatset Weight, 02/1711; (gmJrneter 3.74 (126.7) 3.55 3.47 (126.7) 3.47 (126.7) Bending length (cm Warp 1.9 1.85 1.62 1. 5s 1. 75 1. 72 2. 43 2.18

ments were of a symmetrical trilobal cross-section and contained 2% of a finely divided kaolinite. This yarn was a mixed shrinkage yarn because the copolymer filaments have higher shrinkage than the homopolymer filaments when co-spun and drawn under the same conditions. Uptwist packages containing 0.4 lb. of this yarn having 5Z twists per inch were twist set for 90 minutes under the conditions shown in Table I. Yarns from the twistset packages were subjectively rated for yarn twist liveliness on a scale where 5 is lively and 0 is substantially dead or no twist liveliness with the results shown in Table I. The yarns were then uniformly wound on collapsible paper cores into packages (for shrinking) at 0.5 gm. tension to give a package hardness of 20 units.

The yarn packages are then shrunk in an autoclave with steam at 127 C. for 30 minutes. A non-twist-set control yarn develops 8-9% differential filament length (DFL) due to the mixed shrinkage. The yarn twist-set at F. (71 C.) (dry bulb temperature) shows about the same DFL; higher twist-set temperatures result in reduced DFL; however, the DFL remains acceptable for a twist-set temperature up to 220 F. (104 C.) as shown in Table I. The packages from yarn twist-set at 71104 C.

The unexpected extent and kind of fabric response to heat-setting, with the warp and fill responding in opposing directions, is readily apparent from the data. As shown by the flexural rigidity, fabric firmness of hand increases markedly in the fill and decreases in the warp upon heatsetting above 350 F. (180 C.).

Bending length is defined as the length, in cm. of a strip of fabric of unit width which would be required as a horizontal cantilever to cause the fabric to leave its support on a curve having a unit radius.

Flexural rigidity, derived from the bending length and the weight per unit area of the fabric, is defined as the moment of couple required to bend a strip of fabric of unit width in a circle having a unit radius. It is calculated from the product of the bending length and weight per unit area of the fabric. This value increases as the firmness of hand of the fabric increases.

The fabric samples are cut so as to measure these values in both the warp and fill directions. Bending length is measured by means of a strip of fabric suspended in a heart-shaped loop (a double cantilever). The heart loop test is described in ASTM Standards 1958, Part 10, pub lished by the American Society for Testing Materials,

7 Philadelphia, Pa., pages 557-562. It has the ASTM test designation: D1388-55T, Method B. A fabric sample 1 X 6 /2 inches (2.54 X 16.5 cm.) is used, cut to measure properties for the warp and fill directions as prescribed. The sample is mounted such that the measured specimen length is 6 inches (15.24 cm.).

What is claimed is:

1. Process of preparing a continuous filament yarn by twisting a yarn comprising filaments having differential shrinkages, setting the twist while maintaining the yarn at substantially constant length and thereafter heating the yarn under conditions permitting shrinkage of the yarn characterized in that (a) the yarn comprises a plurality of drawn, oriented synthetic polymer filaments, at least some of which filaments differing in shrinkability from others of said filaments, all of which filaments consist of at least 50% by weight of polymer units of the formula wherein X is 1 or 2, Y is an integer in the range of 7-14 inclusive, R is the same or different and of the class of hydrogen and methyl, at least 40% by weight of the diamino polymer constituent being of a transtrans stereoisomeric configuration, said yarn when subjected to boiling water exhibiting a differential shrinkage between said filaments of at least 1.5% under a load of 4 milligrams per denier said shrinkage ditferential further increasing upon subsequently subjecting said yarns to higher heat-setting temperatures in the dry state under the same load,

(b) the setting of the twist is carried on at a temperature in the range from 70-105 C., r

(c) the shrinkage step is carried on at a higher temperature than the temperature of the twist setting and under conditions of temperature and tension such that from 3 l0% differential shrinkage between at least two groups of filaments develops and such that substantially no further shrinkage takes place during any subsequent dyeing.

2. The process of claim 1 wherein the differentially shrunk yarn is dyed prior to producing fabric therefrom, said shrinkage step conditions being such that substantially no further shrinkage takes place during dyeing. I

3. A yarn of at least two groups of filaments, the filaments in one of said two groups differing from 3 to 10% in length from the filaments of the other of said two groups, the filaments in 'both said groups consisting of at least 50% .by weight of polymer units of the formula:

wherein X is 1 or 2, Y is an integer in the range of 7-14 inclusive, R is the same or different and of the class of hydrogen and methyl, at least by weight of the diamino polymer constituent being of a trans-trans stereoisomeric configuration, the said yarn having a twist multiplier between 0.27 and 1.50 and a liveliness multiplier of less than 0.4.

4. The yarn of claim 3 wherein said two groups of filaments each comprise at least 25% of the filaments in the yarn.

References Cited UNITED STATES PATENTS 3,225,534 12/1965 Knospe 57140 3,416,302 12/1968 Knospe 57-140 3,438,192 4/1969 Ryan 57-440 JOHN PETRAKES, Primary Examiner US. Cl. X.R. 

